They had some stayers racing at our local track at Herne Hill, London last Easter. It was crazy!
I got this photo of one of the rear carbon discs on one of the competitors bikes....check out that chainring...

Not ridden stayer events myself (I'm a sprinter) but my brother has, we've still got a full set of 66-70 chainrings in 144PCD ! (they won't fit on a standard track bike as they catch on the chainstay!!!!)